1. Field of the Invention
This invention relates to rain gauges and more particularly to a gauge for measuring low-to-moderate rainfall rates wherein incremental volumes of rain water are removed from the bottom of a column of the collected rain water, whereby the rainfall rate is calculated by determining the number of increments of rain water removed from the column during a period of time.
2. Description of the Prior Art
Various techniques have been employed for measuring rainfall rates, such as, measuring the flow of water between capacitor plates; measuring the momentum of drops formed from the collected rain and allowed to fall a fixed distance; or measuring the water accumulation with a commercially available tipping-bucket rain gauge. While these gauges have been satisfactory for their intended purposes, they have not been found satisfactory for the measurement of low-to-moderate rainfall rates; for instance, in the order of 0.3 to 30 mm/h. In the case of the commercially available tipping-bucket rain gauge, a two-compartment tipping-bucket arrangement is utilized which tips when a certain quantity of water, usually 8.1 ml, has accumulated in one compartment, thereby emptying that compartment and exposing the other compartment for filling. Because of the relatively large quantity of water required to tip such a bucket arrangement, the best resolution obtainable is in increments of 0.25 mm of rainfall.